<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.10/vue.js"></script>
</head>
<body>
<div id="app">
  <button @click="count++">修改count++</button>
  <button @click="unWatch">取消</button>
  <p>{{count}}</p>
</div>
<script>
    const vm = new Vue({
        el:"#app",
        data(){
            return{
                count:0,
            }
        },
      methods:{
          unWatch:()=>{},
      },
    })

    vm.unWatch = vm.$watch(
            "count",
            function (){
              console.log("count改变了");
              console.log(this);
            },
            {
              deep:true,
              immediate:true,
            }
    );
    </script>
</body>
</html>